"Concentrate on your duty, not on the fruits. Do everything in God’s name and allow Him to worry about the fruits."
Hatha means willpower, and here it refers to disciplined practice and behaviour using willpower and energy.
Hatha Yoga is the path of practice and purification - internal, as well as external. It is therefore an additional Yoga path to the four traditional paths. Regular practice of these exercises requires willpower and discipline and that is why this path is called Hatha Yoga.
HA-THA, also means sun and moon. This refers to the union and harmony of the sun and moon principles, which result from the practice of Hatha Yoga. There are six purification techniques that pertain to Hatha Yoga, called Shat Karma Kriyas or Shat Karmas. In the West, Asanas and Pranayamas are generally assigned to Hatha Yoga - they are actually a part of Raja Yoga.
Caution:
All the techniques described here should initially be practiced under the guidance of a “Yoga in Daily Life” Teacher.